N-(2-methyl-4-chlorophenyl)-formamidines



United States Patent 3,502,720 N-(2-METHYL-4-CHLOROPHENYL)- FORMAMIDINESHorst Arndt, Unna, and Walter Steinhausen, Grossburgwedel, Germany,assignors to A. G. Schering, Berlin, Germany No Drawing. Originalapplication Dec. 20, 1963, Ser. No. 332,255, now Patent No. 3,378,437,dated Apr. 16, 1968. Divided and this application Nov. 15, 1966, Ser.

Int. Cl. C07c 123/00 US. Cl. 260-564 8 Claims ABSTRACT OF THE DISCLOSUREN-(2-methyl-4-chlorophenyl)-formamidine derivatives of the formula R2destroy mites in all stages of development when R is hydrogen or alkylhaving not more than four carbon atoms, and R is such alkyl.

This invention relates to acaricidal agents, more particularly tocompounds which are selectively toxic to acarids, such as mites in allstages of development.

This application is a division of our copending application Ser. No.332,255, filed Dec. 20, 1963, now Patent No. 3,378,437.

We have found that basic compounds of the formula the acaricidal effect,or at least in a substantial reduction 1 of the effect.

,The acaricidal agents of the invention are harmless to insects. Theydestroy mites without damaging insects that may prey on the mites.

The acaricidal agents of the invention are highly effective against miteeggs in their later stages of development. They are therefore useful inthe treatment of plants long after their infestation by mites.

The acaricidal agents of the invention may be prepared by conventionalmethods. In a preferred procedure, an N-formylated monoor dialkylamineis reacted with an equivalent amount of phosphorus oxychloride in thepresence of an inert organic solvent at a temperature between 20 and 100C., and the equivalent amount of 2- amino-S-chlorotoluene is added tothe reaction mixture. The ensuing second reaction yields the amidiniumsalt which is converted to the free base by conventional methods. Thebest time and temperature to be selected for the second reaction variessomewhat for the several compounds of the invention, but is readilydetermined by preliminary small scale tests.

The following example is illustrative of specific conditions which willyield acceptable results, but it will be understood that the inventionis not limited to the process by which the acaricidal agents areproduced.

EXAMPLE 1 15.4 parts by weight of phosphorus oxychloride were slowlyadded with stirring to 7.4 parts by weight of dimethylformamidedissolved in 50 parts by weight of ethylene chloride. The additionperiod was about thirty to forty minutes and the temperature was allowedto rise to 45 C. To the solution then were subsequently added 14.2 partsby weight of Z-amino-S-chlorotoluene while stirring was continuallymaintained and the temperature of the reaction mixture was allowed torise to C. After completion of the 2-amino-5-chloroto1uene addition, themixture was stirred for two additional hours at about 65 C. C. Then thetemperature of the solution was adjusted to about 5 C. by externalcooling, and a strong base such as sodium hydroxide solution ortriethylamine was added with vigorous stirring to maintain the pH at11-11.5. The ethylene chloride layer was separated, washed with water,and dried over sodium sulphate, followed by evaporation of the solventunder diminished pressure which yielded as residue 16.7 parts by weightof an oily liquid, nearly percent of the theoretical amount; B.P.156-157 C./0.4 mm. 72 1.5885 and d 1.105.

The elementary analysis corresponded to that of the compound C H N Cl N(2 methyl-4-chlorophenyl)- N,N-dimethylformamidine:

Found (percent): C, 61.50; H, 7.11; N, 14.53. Calculated (percent): C,61.06; H, 6.66; N, 14.26.

Representative acaricidal agents of the invention when prepared by theabove method have the following characteristic properties.

N (2 methyl-4-chlorophenyl)-N'-methylformamidine:

M.P. 85-87 C.

N (2 methyl 4 chlorophenyl) -N',N' dimethylfor-mamidine: B.P. l56157C./0.4 mm. n =1.5885; d =1.l05

N (2 methyl-4-chlorophenyl)-N,N'-diethylformamidine: Oil n =l.572; a=1.702

N (2-methyl-4-chlorophenyl)-N-n-propylformamidine:

M.P 73-75 C.

N (2-methyl-4-chlorophenyl)-N,N-di-n-propylformamidine: Oil n =l.5545; d=LO25 N (2 methyl-4-chlorophenyl)-N'-isobutylformamidine:

M.P. 81-82 C.

N (2 methyl 4 chlorophenyl)-N'-se c.-butylformamidine: M.P. 42-44 C.

The melting points indicated herein are uncorrected, and were taken onmaterials recrystallized from hexane.

The acaricidal compounds of the invention may be applied singly or inmixtures with each other and with other pesticidal agents. They mayconstitute the active ingredient of dusting compositions, or they may beapplied to mites in fogging or spraying compositions. When incorporatedin liquid compositions, the acaricidal agents of the invention may bedispersed in an inert liquid medium to form a suspension or emulsion.The salts of the formamidine derivatives of the invention with strongacids, such as hydrochloric acid, are soluble in water. The salts arespecifically toxic to mites, and their aqueous solutions may beincorporated liquid acaricidal compositions.

Solid compositions based on the acaricidal agents of the invention mayinclude conventional solid diluents and carriers such as limestone,kaolin, chalk, talcum, lattaclay and other clays. Surfactants whenadmixed to such compositions enhance their elfectiveness in a mannerknown in itself.

The acaricidal properties of the formamidine derivatives of theinvention, and the use of the compounds in the protection of plantsagainst parasitic mites are illustrated in the following Examples whichalso show the results of comparison tests performed with other compoundsclosely related to those of the invention but not encompassed within thescope of the appended claims.

EXAMPLE 2 Effects on acarides in the postembryonal stage and on ova Bushbeans in the late two-leaf stage and infected with spider mites of thespecies Tetranychas urticae Koch in all stages of development weresprayed with aqueous suspensions or emulsions of various formamidinederivatives and with aqueous solutions of formamidine derivative saltsin different concentrations.

The liquids were applied to the potted plants while the same werestanding on a rotating turntable. A spray gun equipped with a glassnozzle was employed. The pressure at the gun was 0.5 kg./cm. The amountof liquid applied to three plants per pot was between 50 and 60milliliters and was sufficient for complete wetting of the plants.Excess liquid ran off in drops.

The iethal effects of the sprayed liquid on the postembryonal mitepopulation, and on the ova was assessed after seven days, except in thecase of N-(2-methyl-4- chlorophenyl)-N,N'-dimethylformamidine, in whichresults were evaluated after 14 days.

4 EXAMPLE 3 Effects on ova of dilferent ages The eifects ofN-(2-rnethyl-4-chlorophenyi)-N,N'- dimethylformamidine on ova of Tetranychus urticae Koch were evaluated in a test based on the method ofS. C. Hoyt, J. of Econ. Entomol. 54 (1) 12-16, 1961. Circular disks of18 mm. diameter were cut from bean leaves by means of a tubularlaboratory cork borer. The leave disks were placed in open Petri disheson foam plastic pads saturated With water which kept the disks fromwilting. Ten adult females of Tetranychus urticae Koch were placed oneach disk, and were removed after one day. On average, they left fiftyeggs on each disk.

The eggs were sprayed with aqueous emulsions containing differentamounts of the acaricidal agents. Spraying was performed by means of aconventional apparatus (dosing balance of M. Ehlers, Nachrichtenblattdes Pflanzenschutzdienstes, 5 (4) -62, 1953'). Ova that had not hatchedeight days after the beginning of the test were considered dead.

The percentages of dead ova in batches sprayed with emulsions containingthe acaricidal agent in different concentrations at different periodsafter iaying are listed below.

Age of ova, days Concentration of active agent in ppm. 0-1 1-2 2-3 3-44-5 Obviously, many modifications and variations of the presentinvention are possible in the light of the above teachings. It istherefore to be understood that the invention may be practiced otherwisethan as specifically disclosed.

What is claimed is:

1. An acaricidal compound of the formula wherein R is a member of thegroup consisting of hydrogen and alkyl having one to four carbon atoms,and

Gone. Efiect, lethal, percent Compound Percent V Postembr. Ova

N-(Z-methyM-chlorophenyl)-N-methylformamidine 3 33 $8 0. 01 100N-(imethylA-chlorophenyl)-N,Ndimethylformamidine b :22

N-(2-methyl-4-chlorophenyl)-N',N-dimethylformamidinium chloride 0. 1000. 02 100 N-(2-methyl-4-chlorophenyl)-N,N-diethylfermamidineN-(2-methyl-4-chlorophenyl)-N',-n-propylformamldine b 3gN-2-methyl-4-chlorophenyl)-NN-di-n-prepylfortma1nidine 22N-(2-methyl-4-chlorophenyl)-N'-isobutylfm'm ml in 3gN-(2-methyl-4-ehlorophenyl)-N-sec.-butylformamidine b; 38N-phenyl-N,Ndimethylformamidine 0 0 As is evident from the abovetabulation, acaricidal effects are closely bound to the specificconfiguration of substituents in the phenyl radical.

R is alkyl having between one and four carbon atoms.

2. N-(2-methyl-4-chlorophenyl) N methylformamidine.

